Electrical switches are able to provide an electrical conductive path in a closed status (on-status) of the switch. To interrupt the flowing current, the switch is opened (off-status). Therefore switching is connecting or disconnecting two contacts. In case of disconnecting the contacts from each other, current flows through the connection until the connection is opened. When an inductive circuit commonly operated in air is switched off the current cannot instantaneously jump to zero; a transient arc will be formed across the separating contacts. An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. Electric arcs in switches operated with AC power will extinguish at latest at the zero point of the AC voltage. In contrast to AC applications, the occurrence and the stability of electric arcs is much higher in switches operated with DC power. Undesired or unintended electric arcing can have detrimental effects on electronic equipment such as switches. If a circuit has enough current and voltage (commonly more than 1 A and more than 50V), the electric arc will not extinguish on its own. Such a permanent arc will damage the contact points (erosion of the contacts) inside the switch. Additionally there is a risk that electric arcs may reach the outside of a switch causing damage to equipment such as melting of conductors, destruction of insulation, and fire causing a hazard to people and equipment. Therefore especially DC switches are normally designed to contain and to extinguish an arc in so-called arc-extinguishing units inside the switch.
Document EP 1884969 discloses a contactor with two fixed contacts and a contact bridge to connect the fixed contacts as a special example of a switch suitable for DC current with an arc-extinguishing chamber to extinguish arcs occurring during opening of the contact points to interrupt the current flowing through the contact points. The contactor comprises a combination of permanent magnets and electromagnets to guide an electronic arc from the contact points to an arc-guiding plate separated from the contact points via an air gap, where the permanent magnets are intended to force the electric arc jumping across the air gap, which is a barrier for the electric arc on its way to the extinguishing chamber. The electromagnets are connected to arc-guiding plates and the fixed contacts to drive the electric arc towards the arc-extinguishing chamber along the arc-guiding plate. The driving magnetic field provided by the electromagnets depends on the current flowing through the electromagnets, which depends on the properties of the electric arc, which may vary. It is desirable to obtain a switch with the smallest number of required parts. It is further desired to obtain a switch, where the electric arc can be extinguished as fast as possible under predictable and stable conditions.
Document EP 2 061 053 A2 discloses a switchgear having a housing with two side panels opposite to each other. Three holding areas are provided for conducting paths parallel to each other. The holding areas are arranged next to one another in the housing between the two side panels. The conducting paths are associated with assigned arc-unloading devices that are arranged in the housing between the two side panels. An alternatively configured switching device for direct-current applications in which the external magnets are magnetically coupled via magnetic return elements is disclosed, wherein the magnetic return elements are additional separate constructions, which are installed only with switches for direct-current applications.